[rubygems/rubygems] Prefer the standard separator on Windows

It seems like the most common case since it requires no tricks on our
CI environment.

Co-authored-by: MSP-Greg <MSP-Greg@users.noreply.github.com>

https://github.com/rubygems/rubygems/commit/751c475574

lib/rubygems/installer.rb

@@ -704,7 +704,7 @@ class Gem::Installer
     return if self.class.path_warning
 
     user_bin_dir = @bin_dir || Gem.bindir(gem_home)
-    user_bin_dir = user_bin_dir.tr(File::SEPARATOR, File::ALT_SEPARATOR) if
+    user_bin_dir = user_bin_dir.tr(File::ALT_SEPARATOR, File::SEPARATOR) if
       File::ALT_SEPARATOR
 
     path = ENV['PATH']

test/rubygems/test_gem_installer.rb

@@ -196,7 +196,7 @@ gem 'other', version
     bin_dir = installer.bin_dir
 
     if Gem.win_platform?
-      bin_dir = bin_dir.downcase.gsub(File::SEPARATOR, File::ALT_SEPARATOR)
+      bin_dir = bin_dir.downcase
     end
 
     orig_PATH, ENV['PATH'] =
@@ -239,7 +239,7 @@ gem 'other', version
     expected = installer.bin_dir
 
     if Gem.win_platform?
-      expected = expected.downcase.gsub(File::SEPARATOR, File::ALT_SEPARATOR)
+      expected = expected.downcase
     end
 
     assert_match expected, @ui.error